Alpha-numberic display type electron discharge device

ABSTRACT

An improved alpha-numeric display type electron discharge device is disclosed having fluorescent coated anode segments raised slightly from a planar insulating substrate. The invention provides conducting portions surrounding the coated portions to inhibit the deleterious effects of charge buildup on the insulating substrate. The raised anode construction of the invention also prevents sublimation from the cathode from forming conducting paths on the substrate between adjacent anodes.

United States Patent 1 [111 3,846,662

Hooker Nov. 5, 1974 ALPHA-NUMBERIC DISPLAY TYPE 3,302,052 1/1967 Schwab 313/1095 ELECTRON DISCHARGE DEVICE 3,418,509 12/1968 Frouws et al. 313/ 109.5

Inventor:

Assignee:

John M. Hooker, Owensboro, Ky.

General Electric Company, Owensboro, Ky.

Filed: June 22, 1970 Appl. N0.: 48,155

US. Cl. 313/496, 313/289 Int. Cl. H01j 61/66 Field of Search 313/1095, 258, 289, 108

References Cited UNITED STATES PATENTS 2/1957 Williams et al. 313/1095 10/1960 Bernstein 313/1095 X 10/1966 Maloney et al. 313/1095 Primary Examiner-Palmer C. Demeo Attorney, Agent, or Firm-Nathan J. Cornfeld; D. A. Dearing; Frank L. Neuhauser [57] ABSTRACT An improved alphanumeric display type electron discharge device is disclosed having fluorescent coated anode segments raised slightly from a planar insulating substrate. The invention provides conducting portions surrounding the coated portions to inhibit the deleterious effects of charge buildup on the insulating substrate. The raised anode construction of the invention also prevents sublimation from the cathode from forming conducting paths on the substrate between adjacent anodes.

4 Claims, 4 Drawing Figures Pmmmuv 19M 3.846562 INVENTOR: JOHN M. HOOKER HIS ATTORN ALPHA-NUMBERIC DISPLAY TYPE ELECTRON DISCHARGE DEVICE BACKGROUND OF THE INVENTION This invention relates to electron discharge devices. More particularly, this invention relates to improvements in an alpha-numeric display type electron discharge device.

Devices for the display of alpha-numeric symbols are known to the art. Such devices include gaseous discharge tubes and cathode ray tubes. The gaseous discharge tubes heretofore described, and in one version thereof, have several disadvantages including high operating voltages and undesirable parallax due to the positioning of the electrodes in the tube. The cathode ray tube types conventionally require costly auxiliary equipment to program the deflection of the electron beam to display a desired symbol.

More recently, a third type of alpha-numeric indicator tube has become known to the art. In this type of tube a series of anode segments, each of which is coated with a substance which will fluoresce under electron bombardment, are mounted in an evacuated envelope. Electrons from a cathode source selectively bombard one or more of the anode segments. The selective bombardment is controlled by selectively energizing one or more of the anode segments.

In the use of such a device, it is known to mount all of the anodes on a planar insulating substrate. The advantages of such a construction include cost, mechanical rigidity, and the absence of parallax due to the planar configuration of the anodes. However, it has been found that in such devices as previously disclosed, an undesirable charge build-up occurs on the insulating substrate adjacent the fluorescent-coated anodes. This charge in turn repels the electrons initially directed toward the fluorescent layer with the result that part of the anode does not fluoresce and the display of the desired symbol is correspondingly impaired. It has been proposed to solve this problem by constructing the conducting anode with a larger surface area than the desired fluorescentcoated area i.e. conducting portions are provided adjacent and surrounding the fluorescentcoated portions of the anode. However, the geometrical space limitations of the display require rather close spacing of the various fluorescing segments. This in turn crowds the conducting portion surrounding each of the fluorescent segments so that only tiny insulating portions remain between the various conducting portions. When such constructions are used, sublimation from the cathodes onto the substrate causes leakage of the voltage on one anode segment to an adjoining anode segment via the conducting paths formed by the sublimed cathode material on the insulating substrate.

It is therefore an object of this invention to provide an alpha-numeric display type electron discharge device wherein fluorescent anode segments are surrounded by conducting material to minimize effects of charge buildup on the insulating substrate while providing means to prevent leakage between adjoining anode segments from sublimed cathode material. Other objects of the invention will be apparent from the description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of the invention.

FIG. 2 is a horizontal cross-section of a portion of FIG. 1 taken along the line llll thereof as seen in the direction of the arrows.

FIG. 3 is an isometric view of a portion of the invention.

FIG. 4 is an isometric view of an alternate construction to that shown in FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT Turning now to FIG. 1, the alpha-numeric display tube of the invention is generally indicated at 2. Display tube 2 comprises an evacuated glass envelope 4 having a series of parallel pins or conducting members 6 protruding from one end of the envelope in a circular arrangement allowing the device to be inserted into a conventional tube socket. Within envelope 4 is a planar insulating substrate 10 which may be of mica, ceramic, or other suitable material. A plurality of conducting anode segments 14 are mounted on substrate 10 in substantially a figure 8 configuration. Each anode segment 14 is partially coated with a rectangular phosphor layer 40 which will fluoresce under electron bombardment from relatively small cross-section cathode wires 60 and 62 mounted in front of and spaced from anode segments l4.

Substrate 10 is mounted generally along the vertical axis of tube 2 and is supported therein by leads 15 which interconnect anode segments 14 with pins 6 as will be described hereinafter. Substrate 10 preferably comprises a synthetic mica material such as MICA- MAT. Alternatively, as previously mentioned, other insulating material can be used.

Each anode segment 14 generally comprises a flat, rectangular conductive plate which is moutned on substrate 10 in a plane parallel to the substrate. Segment [4, in a preferred embodiment, is formed from 5-l0 mil stainless steel stock. Segment 14 is, however, not mounted directly to the substrate but is raised slightly and maintained in this relationship to the substrate by tabs 22 and 32.

As best seen in FIG. 3, segment 14 has portions 20 and 30 at each end which are folded back against the main portion 16 of segment 14. Portion 20 has a tab 22 depending therefrom at a angle. Tab 22 is formed with a wide segment24, shoulders 26 and a narrow finger 28. Portion 30 has a similar tab 32 depending therefrom.

Segment 14 is mounted on substrate 10 in spaced relation thereto by inserting narrow fingers 28 and 38 of tabs 22 and 32 into holes in substrate 10 of approximately the same diameter as the width of fingers 28 and 38. Shoulders 26 and 36 on the respective tabs thus butt against the surface of substrate 10 to maintain the desired spacing of segment 14 from substrate 10. The ends of fingers 28 and 38 emerging from the holes in substrate 10 may be bent, twisted, or otherwise deformed to secure segment 14 to substrate 10.

Alternatively, as illustrated in FIG. 4, segment 14 may be mounted in spaced relationship to substrate 10 by tabs 22' and 32' which comprise end portions of a single strip or ribbon 23 of metal of smaller width than segment 14. Ribbon 23 is then welded or otherwise suitably attached to one surface of segment 14 and each end of the ribbon is bent adjacent the end of the segment to form the tabs 22' and 32'. After passing thru appropriate sized holes in substrate 10, tabs 22' and 32 can then be suitably deformed to secure segment 14 to substrate 10. In this embodiment segment 14 is mounted parallel to substrate yet spaced therefrom a distance equal to the thickness of ribbon 23.

In the preferred embodiment illustrated in FIG. 1, seven segments 14 are mounted to substrate 10 in a generally figure eight shaped arrangement. Each of the seven segments is attached to one of the pins 6 via a conductive lead wire 15 which is welded at one end to pin 6 and at the other end to tab 22 or 32. Seven pins are thus used to conduct the anode voltage selectively to the seven anode segments.

Cathode wires 60 and 62 are both attached at one end to an extension of one of the pins 6a. Conveniently the end of this pin is bent approximately 90 and the two cathode wires 60 and 62 are mounted parallel to one another. The opposite end of each of the cathode wires is attached to lead extensions 66 and 68 respectively which also are attached via a cross member (not shown) to substrate 10. An extension of another of pins 6 is in turn welded to this cross member, thus mechanical support as well as electrical connection to cathode wires 60 and 62 are achieved.

A suitable phosphor such as, for example, a ZnO:Zn phosphor, capable of being excited at relatively low voltages, for example, 10-40 volts and typically about 25 volts, is silk screened over a portion of segments 14 to provide a rectangular shaped fluorescent member 40. While, as illustrated in the drawings, fluorescent member 40 may be located adjacent one edge of the planar surface of segment 14, member 40 is none the less surrounded completely by conducting surfaces. As more clearly seen in FIG. 2, member 40 may be bounded on one side by conducting portion 42 of the planar surface of segment 14 and on the other side by the conducting end surface 44 on segment 14, as well as the conducting rear surface 46 of segment 14. Thus, no portion of insulating substrate 10 directly abuts fluorescent member 40. Charge buildup, therefore, if it does occur on substrate 10 will not inhibit the electron bombardment of member 40 and therefore the entire surface of member 40 will fluoresce uniformly to improve the defmition of the display.

As seen in FIGS. 1 and 2, each raised anode segment 14 is spaced from adjacent segments and, because of its pedestal like mounting to substrate 10, each segment 14 is also spaced from substrate 10. The spacing of segment 14 from substrate 10 provides a shadowing effect over substrate 10 when the spacing is small in comparison with the length andwidth of segment 14. When the mounting means, such as tabs 22 and 32, are spaced from the edges of segment 14, the shadowing effect prevents sublimation from cathode wires and 62 onto substrate 10 from creating a leakage bridge or path between conducting portions of adjacent segments.

Thus, the invention provides an alpha-numeric dis play type electron discharge device of a rugged construction, mechanical rigidity, and low cost, and at the same time improving the quality of the display symbol due to substrate charge buildup or leakage due to sublimed cathode material. Minor modifications of the illustrated embodiment will be readily apparent to those skilled in the art and are deemed to be within the scope of the invention as defined by the appended claims.

What 1 claim as new and desire to secure by letters Patent of the United States is:

1. An alpha-numeric display type electron discharge device comprising: an evacuated envelope containing a cathode, an insulating anode support substrate, and a plurality of planar anode segments mounted on said substrate generally in one plane, each of said anode segments having a coating of fluorescent material on at least a portion of a first surface of said segment and having means on the opposite surface of said segment to space the segments from said substrate an amount that is small with respect to the lateral dimensions of said segments, said spacing means being spaced from the edges of said opposite surface.

2. An alpha-numeric display type electron discharge device comprising:

a. an evacuated envelope;

b. cathode means;

c. an insulated anode support substrate spaced from said cathode means;

d. a plurality of planar anodes mounted on said substrate generally in one plane spaced from said substrate;

e. a coating of fluorescent material on at least a portion of a first surface of each of said anodes;

f. conducting portions on each anode completely surrounding the fluorescent coating on each anode to prevent charge buildup adjacent the coating; and

g. spacing means to space said anodes from said substrate.

3. The device of claim 2 wherein said fluorescent coating comprises an ZnO:Zn phosphor.

4. The device of claim 2 wherein said device is operated in a low voltage range of about 1040 volts. 

1. An alpha-numeric display type electron discharge device comprising: an evacuated envelope containing a cathode, an insulating anode support substrate, and a plurality of planar anode segments mounted on said substrate generally in one plane, each of said anode segments having a coating of fluorescent material on at least a portion of a first surface of said segment and having means on the opposite surface of said segment to space the segments from said substrate an amount that is small with respect to the lateral dimensions of said segments, said spacing means being spaced from the edges of said opposite surface.
 2. An alpha-numeric display type electron discharge device comprising: a. an evacuated envelope; b. cathode means; c. an insulated anode support substrate spaced from said cathode means; d. a plurality of planar anodes mounted on said substrate generallY in one plane spaced from said substrate; e. a coating of fluorescent material on at least a portion of a first surface of each of said anodes; f. conducting portions on each anode completely surrounding the fluorescent coating on each anode to prevent charge buildup adjacent the coating; and g. spacing means to space said anodes from said substrate.
 3. The device of claim 2 wherein said fluorescent coating comprises an ZnO:Zn phosphor.
 4. The device of claim 2 wherein said device is operated in a low voltage range of about 10- 40 volts. 